Method and apparatus for logging drill holes



Aug. 19, 1947. L, DILLON 2,425,868

METHOD AND-APPARATUS FOR LOGGING DRILL HOLES Filed Aug. 28, 1936 2Sheets-Sheet l ug. 19, 1,947. 1 D|| QN 2,425,868

METHOD AND APPARATUS FOR LOGGING DRILL HOLES Filed Aug. 28, 195e- 2sheets-sheet 2 f- 47 l fra /cz lfzy @ad I Y E l f T I .'50 g l f2@ `@wirl l J Y INVENToR. vv/@.7 Lyle Dillon g BY I L? 6 2 70. 43 ATTORNEY.

Patented Aug. 19, 1947 METHOD AND APPARATUS FOR LGGING DRILL HOLES LyleDillon, Los Angeles, Calif., assgnor to Union Oil Company of California,Los Angeles, Calif., a corporation of California Application August 28,1936, Serial No. 98,355

21 Claims. l

This invention relates to drill hole testing and particularly toelectrical and acoustical methods and apparatus for the determination ofthe stratigraphy of earth bore holes such as oil wells.

The primary object of this invention is to provide a. method andapparatus by which subsurface measurements of bore hole stratigraphy,pressure, temperature, inclination and the like can be made within thedepths of the bore hole and by which these measurements can becontinuously transmitted to the ground surface without the necessity ofemploying expensive and troublesome electrical connecting cables- Thebroad invention accordingly resides in a method and apparatus for makingphysical measurements such as formation and iiuid temperatures,pressures and electrical properties and borehole inclinations within thedepths of a bore hole, transforming the measurements into mechanicalvibrations which are proportional to or indicative in character of thesaid measurements, transmitting these vibrations mechanically throughthe fluid in the bore hole or through the supportingv cable or throughthe surrounding formations to the earth surface, detecting andamplifying these virbations at the surface and ascertaining or recordingthe said measurements in accordance with the character of the thusoriginated and detected vibrations. The invention resides morespecifically in a method and apparatus for measuring the electricalcharacteristics of the unitary portions of the penetrated formationstrata within the depths of a bore hole such as an oil well,transferring these measurements into mechanical vibrations, thefrequencies of which are functions of the said measurements, detecting,amplifying and measuring these mechanica1 vibrational freis an optionalarrangement of the apparatus of Fig 2 as it would appear taken onsection line 4 4. Fig, 6 diagrammatically illustrates atemperature-operated device which may be optionally substituted for thegalvanometer G of Fig. 2 when bore-hole temperature readings are made.Fig. 'l diagrammatically illustrates a gravity-operated device which maybe substituted for the galvanometer G in Fig. 2 when bore-holeinclination determinations are made.

The apparatus is as follows:

Referring to Fig. 1, W is an instrument adapted to be lowered by anappropriate steel line or cable I0 into the earth bore hole II. M is anelectrical pickup device such as a crystal, magnetic, condenser orcarbon microphone, geophone or the like device adapted to transformmechanical or seismic vibrations into fluctuating electrical currents ofcorresponding character or frequency. A represents an amplifier of theconventional vacuum tube design capable of great sensitivity andpreferably selective or tunable over the range of frequencies employed.The frequency meter F is adapted to receive and indicate the frequenciesor changes of frequencies of the amplified current from the amplier A.

The instrument W which is that portion of the apparatus adapted to belowered into the bore quencies received at the earth surface anddetermining therefrom the corresponding electrical measurements madewithin the bore hole.

Other objects and novel features of the invention will be evidenthereinafter.

In the drawings, wherein typical embodiments of the invention are shownby way of illustration: Fig. 1 is a diagrammatic sectional elevation ofa well bore hole showing the general arrangement of the apparatus. Fig.2 is an enlarged elevation of the portion of the apparatus which islowered into the bore hole, diagrammatically i1- lustrating theapparatus and electrical circuits enclosed therein. Fig.Sdiagrammatically illustrates an optional arrangement of the enclosedapparatus and electrical circuits of Fig. 2. Fig. 4 shows a crosssectional View taken at line 4-4 of Fig. 2. Fig. 4a shows a side view ofFig. 4. Fig. 5

hole, comprises a. liquid-tight metal cylindrical container I2 enclosingthe electrical apparatus diagrammatically illustrated within the dottedenclosure I5 in Fig. 2, and also constitutes one electrode of theelectrical bore hole testing system. Projecting from the lower end ofthe cylinder I2 and rigidly attached thereto by means of a coaxial,hollow insulating rod I4 through which conductor 50 extends, is anothershort meta1 cylinder I2a constituting a lower electrode.

At the upper end of the metal cylinder I2 above the compartment whichholds the hereinbefore mentioned electrical apparatus, is positioned thevibration producing means which by way of illustration as in Fig. 4comprises a piezoelectric crystal 20 adapted to be electricallyenergized by means of an alternating electric potential which is imposedbetween the lower heavy cylindrical electrode 2l and the upper lightring electrode 22. The lower cylindrical electrode 2| is coaxiallysupported within the upper section of the cylinder I2 and electricallyinsulated therefrom by means of rigid insulating material 23 such asBakelite. The contact surfaces between the electrode 2|, the insulationbushing 23 and the adjacent internal surface of the metal cylinder I2are designed to be liquid-tight at high pressure differentials. Thepiezoelectric crystal 20 rests lightly upon the top of the cylindricalelectrode 2l and fits loosely within the circular recess 24 at the topof the insulating body 23. The ring electrode 22 rests lightly upon thetop surface of the piezoelectric crystal 24 and is retained in place andelectrically grounded to the instrument body by means of springconnection 25 and con ductor 46. A short distance above the top surfaceof the piezoelectric crystal 20 is a flexible corrugated metal diaphragm21 making a liquidtight division between the inner and outer por.. tionsof the upper section of the metal cylinder. The metal diaphragm 21 isclamped and held in liquid-tight contact with the upper end of the metalcylinder I2 by means of threads 28 and the perforated collar 29. Thespace 33 intermediate the top of the insulating body 23 and the plezo..electric crystal 20 and the bottom surface of the metal diaphragm 21 isentirely lled with an insulating oil of low viscosity.

The perforated collar 29 shown in Fig. 4 is open at the top and alsocarries a plurality of holes forming additional lateral passageways fromthe top of the diaphragm to the outside. At the top of the collar 29 isprovided an open topped threaded connection 3| to which the supportingbail 32 is attached. Upon lowering the instrument into the well, fluidtherein is free to flow varound the bail into the top and through theholes 30 of the collar 29. The upper surface of the metal diaphragm 21is thus in physical contact with the drilling fluid in the bore hole andvibrations originated by the piezoelectric crystal are free to passupward through the oil through the metal diaphragm 21 and directlyupward past the bail 32 or outwardly through the holes 30 into thedrilling uid contained in and surroundingthe upper section of theinstrument. The holes 30 in the collar 29 are provided to allow lateralpassage as well as vertical passage of the vibrations into the drillingiiuid within the bore hole, and to minimize accumulation of sand andcuttings upon the top of the metal diaphragm 21.

As the instrument is lowered into the fluid in the bore hole, thehydrostatic pressure of the drilling mud or other fluid in the wellbears upon the metal diaphragm 21 and the resulting force is transferredin turn through the oil and through the insulating body 23 to thesupporting lugs 26. The electrode 2I is electrically connected to theapparatus within the shell through rod 34 which makes liquid-tightcontact through the insulating body 23.

In Fig. is shown an optional arrangement of the mechanism within theupper end of the cylinder I2 of the apparatus W. Here the arrangement ofthe piezoelectric crystal and its associated electrodes aresubstantially the same as that described' hereinabove, but instead ofsupporting the cylinder by means of the steel line connection to the topof the bail'32 the steel line I0 enters the top of the instrument and isattached to a metal disk 35 which is in turn solidly imbedded in anelastic rubber body 36. This rubber body is flexibly held under pressureWithin the top of the cylinder so as to transfer the weight of theinstrument to the steel line I0 through the threaded ring nut 31. Thiselastic rubber body 36 rests under compression in solid contact upon theupper surface of the metal diaphragm 21, and vibrations originating atthe piezoelectric crystal 24 will be transmitted through the oil 33through the diaphragm 21 and by way of the elastic body Referring toFig. 2, the apparatus diagram-l matically illustrated within the dottedenclosure I5 is enclosed within the steel cylinder I2 and is adapted tothe measurement of electrical resistivities of unitary portions ofsurrounding bore hole formations adjacent the cylinder I2 and the lowerelectrode I2a. B represents the four legs of a Wheatstone bridge with alow frequency alternating current source 40 connected across two legsthereof and an alternating` current galvanometer G connected across theopposite two legs thereof. The alternating current supply is of such lowfrequency that inductance and capacitive eiects of the bridge circuit,associated electrical connections and formation are negligible, thereversal of the current serving only to prevent undesirable electrodepolarizing effects. The resistances R1 and Rz may ordinarily be of equalvalue. Variable resistance Ro is employed for obtaining a balancingadjustment of the bridge circuit. Two legs of the Wheatstone bridgecircuit are connected through conductors 49 and 50 across the electrodesI2 and I2a..

The galvanometer G carries upon the end of its moving arm 4I, which is astrip of insulating material, a metal plate 42. Adjacent the metal plate42 is a stationary metal plate 43 of similar size, the two plates 42 and43 constituting the opposite elements of a variable capacity. Theseelements 42 and 43 are connected in shunt to an inductance winding Lwhich in turn constitutes the frequency control portion of aconventional self-oscillating vacuum tube circuit. Such selfoscillatingvacuum tube circuits are well understood and for this reason theapparatus and operation of the vacuum tube oscilaltor will not bedescribed in detail except to indicate that the piezoelectric crytal 2Uis connected to the plate output circuit thereof between electrodes 2|and 22 by means of electrical conductors 45 and 46. Inductances 41 and48 serve to prevent the alternating component of the plate outputcurrent from being short circuited through the plate voltage supplybatteries.

Fig. 3, as stated hereinabove, illustrates an optional arrangement ofthe apparatus enclosed within the dotted rectangular enclosure I5. Herethe conventional self-oscillating vacuum tube vcircuit is retained asbefore, but the inductance L is connected through the series condenser44 directly in` shunt to the electrodes I2 and I2a by means of theconductors 49 and 50 respectively. This circuit is thus adapted tomeasure directly variations in the dielectric properties of unitaryportions of penetrated formations surrounding the bore hole and adjacentthe two said electrodes.

The hereinbefore described electrical pickup device M may be positionedas shown in Fig. 1 either by partial immersion in the drilling fluid atthe top of the bore hole I I as shown at 60 or in contact with the earthsurface or liquid within a shallow hole at the earth surface, as shownat 6I, or in the case where the mechanical vibrations are transmittedthrough the supporting steel wire I0 as shown in the arrangement of Fig.5, the pickup device may be connected through suitable linkages to apulley which contacts the said steel wire I0 in a manner adapted totransfer the longitudinal vibrations through the steel wire to thepickup device as shown at 62. The apparatus for transferring themechanical vibrations from the steel wire I0 to the electrical pickupdevice M as shown at 62 may comprise three pulleys making contact withthe Wire line and staggered as shown so as to produce a slightly angulardeflection between the two outermost pulleys. Tension is thus appliedagainst the middle pulley 63 from which the vibrations are transmittedthrough the linkage 64 to the said pickup device M. Electricalconnection is made between the pickup device M to the amplifier Athrough a pair of conductors 61. The amplier A is in turn connected tothe frequency meter through a pair of electrical conductors 68.

The operation is as follows, considering first the apparatus as shown inFigs. l, 2 and 4: Prior to lowering the well testing apparatuscomprising the cylinders I2 and I2a into the fluid-filled bore hole, theresistance Ro in the Wheatstone bridge B of Fig. 2 is adjusted to such avalue that for all the changes of measured formation resistivities, therange of motion of the galvanometer G, due to the resulting unbalance ofthe Wheatstone bridge, will be suitable. This adjustment may beascertained by preliminary test runs in an artificial bore holecontaining drilling mud of the type employed in'the well to be tested orby short preliminary runs within the actual-bore hole to be tested. Asthe testing apparatus is lowered into the bore hole and the metalsurfaces of the cylinders I2 and I2a which constitute the testingelectrodes pass adjacent the edges of penetrated strata, the variationsin resistance due to the dierent 'resistivities of the adjacentformations upon motion of the apparatus through the bore hole results ina balancing or unbalancing of the Wheatstone bridge B depending upon thebefore-mentioned adjustment of resistance Ro. The resultant motion ofthe elements of the galvanometer G causes motion of the condenser plate42 relative to the opposite condenser plate 43. This relative motion ofthe condenser plate 42 will thus be a function of the changes ofresistivities of the formations which are brought adjacent to the saidelectrode surfaces I2 and I2a of the testing apparatus during its motionthrough the length of the bore hole. Since these condenser plates 42 and43 are electrically connected in shunt to the inductance L, whichcombination comprises the frequency control circuit of theself-oscillatory vacuum tube circuit, the frequency of the outputelectrical current therefrom will be varied in accordance with thefunction of the said resistivity changes.

The alternating current output of the thus controlled vacuum tubeoscillatory circuit is impressed through the connecting conductors 45and 46 upon the piezoelectric crystal 20 which lies between theelectrodes 2| and 22. Since it is the property of a piezoelectriccrystal to change its linear dimensions in accordance with a function ofthe impressed electric potential upon its surfaces, the piezoelectriccrystal 20 will be set into vibration at a. frequency corresponding tothat of the output of the vacuum tube oscillatory circuit. Thepiezoelectric crystal thus set into vibration transfers these vibrationsto the surrounding material which, in the present case, as illustratedin Fig. 4, comprises the oil, the metal diaphragm 21, the drilling uidwithin the collar 29 below the bail 32 and thence to the drilling fluidcolumn within the drill hole and to the surrounding formation insuccession.

The Vibrations thus transferred to the drilling iiuid within the holeand the surrounding formation Will be transmitted upwardly to the earthsurface where they are received by means of the electrical pickupdevices M placed either at the 6 surface of the drilling nuid shown ator upon the earth surfaceas shown at 6 I. When employing thepiezoelectric crystal pickup device or crystal microphone, the processis in reverse to that employed for generating the vibrations at theinstrument within the bore hole. That is, the earth or mud vibrationsare received and transferred to the piezoelectric crystal surfaces asvibrational pressure changes resulting in corresponding fluctuatingpotentials to be generated upon these crystal surfaces and these smallpo tential difference fluctuations are then transferred through theconductor 61 to the amplifier A where a greatly magnified alternatingcurrentn of corresponding characteristic is generated.

This greatly magnified alternating current is conducted through 68 tothe frequency meter F which is capable of discriminating between thedifferent frequency characteristics of the thus amplified current. Thefrequency meter F may be of any of the well known types such as forexample one similar to that commonly employed for measuring highfrequency electrical currents such as the wave meter. Such a frequencymeter generally comprises an electrical oscillatory circuit of variablenatural frequency characteristics and means such as a galvanometer toindicate resonant conditions. The frequency characteristics of such anapparatus are generally varied 4by means of a variable capacity. Such afre- -quency measuring device may be here employed and if desired thevariable capacity adjustment for determining the condition of resonancemay be directly calibrated in terms of resistivity measurements withinthe bore hole.

Other measurements besides resistivity within a bore hole are desirable,however, as stated before. For example, the dielectric characteristicsof the surrounding formations within a bore hole can be measured. Whensuch dielectric measurements are to be made the electrical apparatusdiagrammatically shown within the dotted enclosure I5 of Fig. 3 issubstituted for that of Fig. 2. In this case the inductance L isdirectly connected through the condenser 44 and through the conductors49 and 50 to the cylindrical metal elecltrode surfaces I2 and I 2a. Thesurfaces I2 and I2a. thus as plates of a condenser, the capacity ofwhich is in shunt to the inductance L of the thermonic vacuum tubeoscillatory circuit, and they are charged by the oscillatory currentgenerated thereby. Since the current by which the electrodes I2 and I2aare thus directly energized is of high frequency, the effects of thepresence 'of adjacent formations upon the effective capacity between theelectrodes I2 and I2a and across the inductances L, is thatpredominantly due to theirdielectric properties.

The portion of the penetrated formations adjacently extending betweenthe electrode surfaces I2 and I2a and included in the electric fieldtherebetween, constitutes that elementary formation unit which is testedfor each given instrument position within the bore hole. Dotted line I3indicates the approximate path of the electric eld through theformation.

Changes in dielectric properties of adjacent formations during motion ofthe testing apparatus within the bore hole, therefore, effects a changein the capacity across the inductance L and thereby changes thefrequency of oscillation of the vacuum tube oscillatory circuit. Thisvariable frequency electrical output of the vacuum tube circuit is inturn impressed upon the piezoelectric crystal 20 and the resultingvibrations transmitted Y,of the testing apparatus as describedhereinbefore,

these vibrations are transferred from the piezo- -electric crystal 20through the oil, the metal diaphragm 2l and the rubber 36 to the metalydisk 35 and thence as longitudinal vibrations through the steelsupporting cable I to the ground surface. 'Ihe vibrations thustransferred to the steel supporting cable I0 are picked up andtransformed to electrical impulses by means of the pickup device M at62, the vibrations being transferred as before described from the cablethrough the pulley I63 and through the connecting linkage 64.

Frequencies employed preferably range from approximately 10,000 to100,000 vibrations per second, the frequencies preferably being aboveaudibility whereby extraneous undesirable noises which might vitiate orinterfere with making the proper readings, are largely eliminated fromthe receiving apparatus. These frequencies from an electrical standpointare relatively low and therefore large values of inductance and capacityin the variable electrical circuits by which the transmitting vibrationsare generated are necessary. For this reason it is sometimes desirableto employ means not only to vary the capacities but also to vary theinductances of the oscillatory circuits as well. Such a variation of alarge inductance may be accomplished by -appropriately controlled,variable electromagnetic circultsassociated with the inductances.

Other measurements which may be made within the bore hole utilizingapparatus similar to that illustrated in Fig. 2 are temperature,pressure, and bore hole inclination.

When uid temperature measurements are made within the bore hole atemperature-operated device such as a bimetal element thermometer issubstituted for the galvanometer shown in Fig. 2. The capacity of thesystem comprising the two plates 42 and 43 is by this means varied inaccordance with changes of temperature. The thermometer is preferablyplaced in the instrument in a position to readily partake of thetemperature of the surrounding drilling fluid and formations.

When it is desired to measure the inclination of the bore hole apendulum-operated device such as illustrated in Fig. 7 is likewisesubstituted for the galvanometer G and thev movable plates 4i and 42 inFig. 2 whereby variations in deviations from the vertical of the borehole in which the instrument is lowered,` activates a variation indistance and hence the capacity between the pendulum element 'l0 and thering 1| and thus varies the frequency of the vacuum tube oscillatorcircuit as hereinbefgore described. The pendulum 'l0 is universallypivoted at 'l2 so that it is free to remain in a vertical positionWithin the instrument W While the ring 1l is rigidly supported in afixed position therein. Deviation of the instrument from theperpendicular will thus cause the pendulum element 10 to move toward thering 1l reducing the electrical capacity therebetween as just stated,

While piezoelectric means has been disclosed as tions within the borehole, other well known means are obviously applicable to the circuitsdescribed and, illustrated herein. For example, the well known dynamicoscillator or vibrator comprising an' electrical circuit in an intenseelectromagnetic eld such as employed for submarine signaling may beemployed. l

While only a single stage thermionic vacuum tube oscillator isillustrated herein, additional stages of amplication may obviously beemployed to obtain a greater intensity of crystal or vibratorexcitation.

Instead of employing continuous vibrations which are controlled infrequency according to a function of the measurements to be made withinthe bore hole, intermittent vibrations may be employed, the timeinterval of which is similarly a function of the desired measures.Vibrations in the audible frequency range can also be employed.

The foregoing is merely illustrative of the method and apparatus of theinvention and is not intended to'be limiting. The invention includes anymethod and apparatus which accomplises the same results within the scopeof the claims.

Iclaim:

l. A method for transmitting indications of physical conditions within abore hole to the earth surface comprising varying the characteristics ofan electric current in accordance `vith a. function of the said physicalcharacteristics in the bore hole, converting said electric current intomechanical vibrations of a character correspon'ding to the character ofsaid current and detecting and receiving saidv vibrations at the earthsurface whereby the physical conditions within the bore hole may bedetermined.

2. A method for transmitting instrument readings/from within a. borehole tothe surface comprising varying the characteristics of an electriccurrent in accordance with afunction of the instrument reading in thebore hole, converting said current into mechanical vibrations corre--sponding to the character of said current, and detecting and amplifyingsaid vibrations at the surface whereby the instrument reading within thebore hole may be determined.

3. A method of transmitting physical measurements from within a borehole to the earth surface comprising varying the characteristics of anelectric current in accordance with a function of the said physicalmeasurements in the bore hole, converting said current into mechanicalvibrations of a character corresponding to said current, transferringsaid vibrations to the-.earth formations surrounding the bore holewhereby the said vibrations are transmitted through the formations tothe earth surface and detecting and measuring the character of the saidvibrations thus transmitted to the earth surface whereby the physicalmeasurement within the bore hole may be ascertained.

4. A method for transmitting indications of physical conditions withinlabore hole to the earths surface comprising generating mechanicalvibrations in the bore hole, controlling the frequency of saidvibrations in accordance with a known function of the physicalconditions therein, transmitting said vibrations from within the borehole to the earths surface, detecting said vibrations at kthe earthssurface and measuring the frequency of said detected vibrations wherebythe first mentioned physical conditions the method for generating themechanical vibrawithin the bore hole may be determined.

5. A method of logging a borehole comprising varying the frequency of analternating electrical current in accordance with a function of theelectrical properties of a unitary portion of the formation surroundingthe bore hole, converting said alternating current into mechanicalvibrations of a corresponding frequency within the bore hole wherebysaid mechanical vibrations are transmitted into and through thesurrounding earth formations and whereby a portion of the vibrationalenergy reaches the earth surface, and detecting and measuring thefrequency of the mechanical vibrations at the earth surface whereby therelative properties of the said unitary portions of the formation may bedetermined.

6. A method of logging a bore hole comprising surface whereby theinclination of the bore hole may be determined.

10. Apparatus for transmitting indications of physical conditions withina bore hole to the earth surface comprising an instrument adapted to belowered into a well bore hole, said instrulowering an instrument whichis sensitive to electrical properties of unitary portions of thesurrounding formations through the bore hole, generating mechanicalvibrations within the instrument in the bore hole, controlling thecharacter of said generated vibrations by said instrument in accordancewith a function of the said changes of the electrical properties of theunitary portions of the surrounding formations as the instrument movesthrough the bore hole, transferring said mechanical vibrations whereby aportion of the vibrational energy reaches the earth surface anddetecting and measuring the changes of the character of the mechanicalvibrations at the earth surface which vibrations correspond to the saidfunction of the changes of the electrical properties of the unitaryportions of the formations surrounding the bore hole.

'7. A method of logging a bore hole comprising lowering on a supportingline an instrument which is sensitive to electrical properties ofunitary portions of the surrounding formations through the bore hole,generating mechanical vibrations within the said instrument in the borehole, controlling the character of said generated vibrations by saidinstrument in accordance with a function of the said changes of theelectrical properties of the unitary portions of the surroundingformations as the instrument moves through the bore hole, transferringsaid mechanical vibrations to the supporting line whereby a portion ofthe vibrations are transmitted longitudinally through the said line tothe earth surface, detecting and measuring the changes of the characterof the said vibrations arriving at the earth surface through the said.supporting line which vibration changes also correspond in character tothe said function of the changes of the electrical properties of theunitary portions of the formations surrounding the bore hole.

8. A method for transmitting indications of the temperature within abore hole to the earth surface comprising generating mechanicalvibrations in the bore hole of a character which is a function of thetemperature conditions therein, transmitting said vibrations from withinthe bore hole to the earth surface and detecting said vibrations at theearth surface whereby the temperature within the bore hole may bedetermined.

9. A method for transmitting indications of the inclination of a borehole to the earth surface comprising generating mechanical vibrations inthe bore hole of a character which is a function of the inclinationsthereof, transmitting said vibrations from within the bore hole to theearth surface and detecting said vibrations at the earth ment comprisingmeans for generating an alternating electrical current, means to controlthe frequency of s aid alternating current in accordance with a functionof the said physical conditions within the bore hole to be measured,means Ato generate mechanical vibrations corresponding in frequency withsaid alternating current, and means to transmit said mechanicalvibrations to the earth surface.

11. Apparatus according to claim 10 in which the means to transmit themechanical vibrations to the earth surface comprise a line by which theinstrument is lowered into the well bore hole.

12. Apparatus for transmitting indications of the electrical propertiesof unitary portions of the penetrated formations surrounding the borehole comprising an instrument adapted to be lowered into a well borehole, said instrument comprising a thermionic .vacuum tube oscillator,means to vary the frequency of the electrical oscillations of saidoscillator in accordance with a function of the variations in electricalproperties of unitary portions of the penetrated formations surroundingthe bore hole as the instrument moves therethrough, electrical means totransform the thus generated and controlled electrical oscillations intomechanical vibrations of corresponding frequency, means to transmit saidmechanical vibrations from said instrument in the bore hole to the earthsurface and a microphone at the earth surface to receive and transformthe vibrations i'nto an alternating current of Icorresponding frequency,means to amplify said alternating current from the microphone, and meanscapable of indicating changes in said amplified alternating currentfrequency.

-13. Apparatus according to claim 12 with means to vary the frequency ofthe electrical oscillatigns of said oscillator in accordance with afunction of the variations in dielectric properties of the unitaryportions of the penetrated formations surrounding the bore hole.

14. A method according to claim 4 in which the said generated mechanicalvibrations are supersonic.

15. Apparatus' for determining inclination tion to be measured, meansfor generating an elastic vibration, means for varying the frequency ofsaid elastic vibration in response to the inclination of said body, andfrequency measuring means responsive to said elastic vibration.

16. Apparatus for determining inclination at a remote locationcomprising a body adapted to assume the inclination to be measured,means at said location for generating an elastic vibration, means forvarying the frequency of said elastic vibration in response to theinclination of said body, means for conducting said elastic vibrationfrom said remote location to a place of measurement, and frequencymeasuring means responsive to said elastic vibration.

1'?. Apparatus for determining inclination comprising a body adapted toassume the inclination to be measured, means for generating an elasticvibration, means for varying the frequency of said elastic vibration inresponse to the inclination of said body, means for translating saidelastic vibration into a varying electric potential 11 difference ofcorresponding frequency, and electrical measuring means responsive tosaid frequency.

18. Apparatus for determining inclination at a remote locationcomprising a body adapted to assume the inclination to be measured,means at said location for generating an elastic vibration, means forvarying the frequency of said elastic vibration in response to theinclination of said body, means for conducting said elastic vibrationfrom said remote location to a place of measurement, means at said placefor translating said elastic vibration into a varying electric potentialdifference of corresponding frequency. and electrical measuring meansresponsive to said frequency.

19. Apparatus for determining inclination of a hole comprising, incombination: a body in said hole adapted to assume the inclination ofsaid hole, means for setting up inY said body an elastic vibrationdependent in frequency upon the inclination of said body, elastic meansextending into said hole and attached to said body for the supportthereof and for transmission of said elastic vibration, and means at thetop of the hole for measuring the frequency of the elastic Vibrationtransmitted through said elastic supporting means.

20. Method of transmitting data from a subsurface prospecting instrumentto surface apparatus that comprises creating an electrical oscillationat the prospecting instrument, altering said oscillation in accordancewith data from said instrument, translating the electrical oscil- 12lation into mechanical vibrations. transmitting the vibrations to thesurface, analyzing the vibrations at the surface to obtain the desireddata, and operating the indicating apparatus in accordance therewith.

l said current, translating the electrical oscillation into mechanicalvibrations, transmitting the vibrations to the surface, analyzing thevibrations at thesurface to obtain the desired data, and operating theindicating apparatus in accordance therewith. LYLE DILLON.

REFERENCES CITED The following references are of record in the iile ofthis patent:

